In a decision to be published tomorrow, Manhattan federal court judge Richard Berman wrote that Craigslist wasn’t at fault for the gun purchase because it was not the publisher of the ad. Publishers of “third party content” are immune from prosecution under the Communications Decency Act of 1996.

Boutique owner Charles Gibson’s complaint claimed Craigslist “is either unable or unwilling to allocate the necessary resources to monitor, police, maintain and properly supervise the goods and services” sold on its site. Gibson was shot six times, and sued Craigslist for $10 million dollars.

Of course, the real question in this case is this: how a schizophrenic man from New York was able to qualify for a permit to purchase a gun in the first place? This seems to fly in the face of New York’s strict gun laws and Mayor Mike Bloomberg’s efforts to prosecute out-of-state gun dealers for selling guns that end up getting trafficked to New York.

Even if Craigslist isn’t legally responsible, clearly founder Craig Newmark takes it to heart when people use his site for the wrong reasons. Not long ago, and amidst public pressure, he attended the funeral of a woman who was murdered after she went to the home of a man who placed a baby-sitting ad on the site.

But there’s a big difference between this lawsuit and the “Craigslist Killer” cases. In this case, we think Craigslist should bear some responsibility. A gun is a known lethal product, and a seller of guns must have a license to do so.

While it would be almost ridiculous to expect them to vet the backgrounds of people who put ads up on their site, Craiglist could easily check gun licenses, and it should. Its service is an ideal medium for anyone who might try to bypass gun laws and sell to people like Jesus Ortiz — the man who shot Charles Gibson last July.